The diagram is based on data from Department of Energy and Climate Change, DUKES 2011 and Energy Saving Trust 2012. Absolute figures are given for the different sources at the top in the diagram, and for the amount of energy “left after production” (328.3 TWh). So mainly it is the (non-)efficiency of the production expressed as relative percentage figures that is shown.

One interesting thing about this energy flow Sankey is that it distinguishes between “Thermal” (yellow) and “Renewable” (green) sources of electricity. This is in contrast to the classic renewable/non-renewable split, since in this diagram biomass falls under thermal sources. Interesting.

High-res PDF with the diagram can be found here. There is also another Sankey diagram in the original PDF that shows the consumption of energy in private homes. Will show that one in a separate post some other time.

The report has numerous other Sankey diagrams like this one, similarly structured. They show energy use of coal, petroleum, natural gas, and renewables.

Below is the one on petroleum flows in 2009 in millio tons. A lower threshold has been introduced, so that small quantities don’t fall below a minimum width (see, for example, the flow of 0.7 mio tons to “Rail”, compared to the one of 4.9 mio tons to “Industry”, which would in principal be 7 times wider if it was to scale.

A reader of the blog alerted me about a new report that contains Sankey diagrams for the United Kingdom’s 2007 and 2050 energy flows. Thanks, Neil!

The report is about heat demand and CHP (Building a roadmap for heat. 2050 scenarios and heat delivery in the UK) and was prepared by University of Surrey and Imperial College for the Combined Heat and Power Association (CHPA). [Account is dead in 2018, access the report here instead]. On p. 18 it has the following Sankey diagram. I have shown a similar diagram for the UK in this post.

The second Sankey diagram presented (on page 23) is a scenario for 2050. It was calculated using the MARKAL model.

One must read all the assumptions made for the model to be able to interpret it, but you can see immediately that the “energy system in 2050 is signifcantly altered under the common assumptions presented in all-electricity scenarios. In particular, final energy consumption in 2050 will be reduced by 46% against 2007 figures under the assumptions used in the CCC 80% CO2 reduction scenario”.

I invite you to read chapters 3.3. and 3.4 of the report to better understand the 2050 Sankey diagram. Note that the overall primary energy demand is significantly lower, but power generation almost doubles compared to the current situation. Losses from oil refineries are omitted in this scenario due to lack of data.

A great Sankey diagram by the research group made up from researchers from ICEPT (Imperial Centre for Energy Policy and Technology) and Centre for Environmental Strategy at the University of Surrey.

What is CHP? “CHP systems are highly efficient, making use of the heat which would otherwise be wasted when generating electrical or mechanical power (…) and typically has an efficiency of over 80%”, the accompanying text explains.

The diagram is built similarly to this one presented in a previous post: The Sankey diagram doesn’t feature absolute figures, but flows are scaled in relation to the baseline of 100 units energy generation in a power plant and a CHP unit. In a cogeneration unit 160 units of energy would be produced at the same time. Losses are accounted for with 65 units in the CHP. To produce the equivalent energy quanities in a conventional power unit would cause losses 1.65 times higher than the energy output itself. In the boiler 25 % of the energy is lost (40 units).
Overall losses in convential generastion are 205 units compared to 65 units in a CHP.

For the UK these Sankey diagrams are published by BERR (Department for Business, Enterprise and Regulation). Historic charts back to 1974 can be found on their website.

UK Energy Flows 2007, by BERR, via The Oil Drum: Europe

A commentor to Chris Vernon’s original post added the Swiss version of this Sankey energy flow diagram originally published by Swiss Bundesamt für Energie (BFE):

These Sankey diagrams have some nice details, which a worth a mentioning: The UK diagram shows stock increases and decreases with circles. The size of the circle has no significance, but the magnitude of the in and out flows seem to be to scale, thus allowing to see if the stock has increased or decreased in that year. Losses at transformation steps are shown with “hanging arrows” (the flows branching off to the bottom line of the diagram). The Swiss version also shows exports this way, but visualizes losses with a pin with a big round head.

Even though your run the risk of being overwhelmed by a gloomy feeling when your read through the comments to Chris Vernon’ post, I would like to draw your attention to a comment by “realist” on Sept 5. He writes: “Deceptive graph! Why show losses for electric power generation and not transportation? The heat losses from the internal combustion engine in most transport is 70-80%”. This is true, but I have always understood that losses explicitly shown in these energy flow Sankey diagrams are the losses occuring in the energy generation, conversion and grid, while losses in the energy consumption (such as use for transport) are not shown. This let alone that they are worthwile to discuss.

The site has a demonstration of how Sankey diagrams may be used to represent transfer of energy, including a PowerPoint and “stories”, for which pupils can create a Sankey diagram by using tokens cut from cardboard.

I think this is a great idea, as it supports the understanding of the energy topic with a haptic and, very importantly, a visual approach.